I will be tuning my car in the future and I'd like to get all of the base work laid out when it comes to tuning this. I'm well versed in OBDII tuning and have done everything to my 1996 Beretta but this OBDI stuff is throwing me a curve ball here.

I'll start with what I have. It's a 1990 Chevrolet Beretta with a 3.1MPFI engine and 3t40 transmission. This is also equipped with the digital dash if that matters. The two numbers I have to go off of is the ECU number and the Prom. The ECU is a ACDelco reman that was installed prior to me owning the car, PN 88999196 The chip has the indetifier of AUPC 2004 stamped on it. Now the issue I'm running across is the fact that no masks include the 1990 3.1 L-car as an option. I'm finding $A1 but that says 91-93 and then $3A for 86-89 J-cars. I see NO listings for the 88-89 2.8 and 90 3.1 L-car. Also searching the AUPC chip has resulted in nothing in the tuning world, I can't find it listed on any charts.

Any insight on which def I should be using as well as what I need for ALDL communication would be great.